I suspect the cardboard cores of the tap rolls could've been used to maybe make slightly more viable cups and dinnerware.
I agree with your problems with the episode, Christopher, but I think the episode was pretty good and did showcase some of the ingenuity behind Jamie and Adam, I did find it interesting how they said the duct-tape catamaran they built was their most "successful" improvised boat they've done on the show. It's impressive to me it made it through the breakers and the only water it took on seemed to be due to poor canoing.
The show didn't much address this but I suspect in a "realistic" situation some-kind-of navigation equipment could have been improvised in order to prevent them from rafting back to the very place they just left. (A "joke" I saw coming a mile away.)
And, yeah, I suspect they weren't "really" strained for food, water or even shelter and that there was a "Man v Wild" thing going on where they were given provisions when the camera weren't rolling. I also suspect they used more than the number of rolls we saw them "given" at the beginning of the episode.
The episode certainly reeks of a lot
of contrivances but, again, it's interesting to see Jamie and Adam using some ingenuity and brains to come up with stuff and to how versatile something can be with the right applications.
On the solar still I wonder if it would have worked with a duct tape drape over it the pit. I mean it doesn't have to be a clear material for it to work just something
for evaporating water to collect on and by making a tarp with both sides being the "non-sticky" side of the tape I suspect a suitable collection drape could have been made.
The sun would heat "Side A" of the duct-tarp which would cause the area under it to heat up and cause the evaporation process. Sure the plastic tarp maybe was more efficient, but I don't think it would have been 100% necessary.